Passing parameter/generic to the top level in Quartus/tcl?

The answer is no. The passing of generics to top levels in quartus has been fairly limited for a long time. You're limited to strings, integers, booleans.

You could probably pass it in as a string and have the HDL parse the string into a sensible value. The annoying part you'll find though, is that Quartus doesnt support textio during synthesis, so you'll probably have to write your own conversion function.